I meet a problem about PLL chip's controlling .
I use TMS320F28335 (DSP) to control the HMC833 (PLL) . I have checked the hardware and software over and over again. Both of them are correct . Furthermore, I confirm the clock of SPI is lower than 10MHz through delay function . But the signal is still not appeared.
The same PLL , I use MCU to control it . It output correctly. And I use ARM to control it , the output is also correct.
MCU,ARM and DSP is different in system clock . The system clock of MCU and ARM is lower than 30MHz. The system clock of DSP is 125 MHz. But I have decreased the clock of SPI through delay function.
It's worth paying attention to the SPI line, it's guide line soldering and not PCB wiring. Concerning this , I have decrease the SPI clock cycle in 2.5 ms.
I really don't know where I didn't notice . Can you give me some suggestions.
After power-on the HMC833 will wait for a rising edge on SEN or SCLK:
If there is any noise or uncontrolled transitions on the SPI lines from your controller after power-on the HMC833 may enter the wrong mode. Check if you can toggle LD/SDO (pin 33) by writing the following sequence:
Reg 0x0F=0xC0 sets LD/SDO low
Reg 0x0F=0xE0 sets LD/SDO high
If the pin does not toggle the HMC833 may be operating in the wrong SPI mode.
Thanks for your reply . It works effectivly.Thanks again.
I have a issue . I want to design a TDD transceiver . I choose the HMC392ALC4 as LNA. The chip of HMC392ALC4 need to be controlled in the mode of TDD. It need to be powered on and off.But I didn't find the response time in the datasheet. Can you help me confirm the response time of Powering on and off . Thanks very much .
Look forward to your good message.
The switching time of HMC392ALC4 alone will typically be below 1uS. Would that meet your requirement, if not for switching times below that we need to check?
ps. If you can open a new EZ post for question about another part, you will be able to get a faster response.
Thanks for your reply.
First, the switching time of HMC392ALC4 is meet my requirement.
Second, I'm sorry that I didn't open a new EZ post for my new question. I will do it as you said.
Last, thanks for your reply again.